A sexually mature male with cheek flanges, throat pouch, and very long fur.
Why would a sexually mature male orangutan want to look too young to father children? Just ask male dung beetles or goby fish. All these species have two types of males: big, aggressive ones that elaborately woo females and smaller sneaker males who, well, sneak behind the backs of the bigger ones. Both can end up successful fathers.
Male orangutans become sexually mature around age 10, but some will stay in arrested development for up to 20 years, even after fathering children of their own. These immature-looking males don’t have the broad cheek flanges, throat pouches, and long orange hair we normally associate with male orangutans. They also don’t produce the long calls that mature-looking males use to attract mates. Even with none of these secondary sex characteristics, male orangutans can get mates and have children. A previous study that tracked an orangutan population in Sumatra for 27 years found that 6 of 11 new babies were fathered by the immature-looking males.